Fungicides control various phytopathological diseases by interrupting various metabolic pathways within the fungal organism. Thus different fungicides may control the same disease, but by different modes of action. Many organisms, however, can develop resistance to a particular mode of action over time. Thus, having available fungicides which act by various modes of action is important to adequately control most diseases.
One mode of action is the inhibition of the succinate dehydrogenase (SDH) enzym in the respiratory pathway of fungi. This mode of action has previously been demonstrated for control of basidiomycetes. For example, carboxin is a commercially available fungicide which exhibits this mode of action against various basidiomycetes. Drouhot et al. ["Properties of Botrytis cinerea Mitochondria and Effects of Various Toxicants Including Fungicides," Pesticide Science, 30:415-417, 1991] have suggested that such a mode of action for control of ascomycetes, such as Botrytis sp., is needed to overcome resistance problems. In their tests of respiratory inhibition, carboxin exhibited a 68% inhibition at 1 .mu.M concentration and was judged the best fungicide of those tested for SDH mode of action against Botrytis.
Pyrazolecarboxamide fungicides are known in the art. U.S. Pat. No. 4,134,987 (Huppatz, Jan. 16, 1979) discloses various N-(phenyl)pyrazolecarboxamides. U.S. Pat. No. 4,742,074, issued May 3, 1988, to Nishida et al., discloses various N-(substituted-indanyl)pyrazole-4-carboxamides useful as fungicides for various agronomic diseases.
It is an object of this invention to provide compounds having a high level of activity in SDH inhibition in ascomycetes. It is a further object of this invention to provide compounds having a broad spectrum of activity against fungal diseases of plants. It is a further object of this invention to provide methods of controlling or preventing fungal diseases of plants. It is a still further object of this invention to provide fungicidal compositions useful in carrying out those methods.